Unit Tests

Additional Resources

• Testing in Rust - Part 2

Exercises

Asserting 1

// Make the test compile and pass successfully.

#[cfg(test)]
mod tests {
    #[test]
    fn you_can_assert() {
        assert!();
    }
}

#![allow(unused)]
fn main() {
#[cfg(test)]
mod tests {
  #[test]
  fn you_can_assert() {
      assert!(1 == 1); // use any expression that evaluates to true
  }
}
}

Asserting 2

// Make the test compile and pass successfully.

#[cfg(test)]
mod tests {
    #[test]
    fn you_can_assert_eq() {
        assert_eq!();
    }
}

#![allow(unused)]
fn main() {
#[cfg(test)]
mod tests {
  #[test]
  fn you_can_assert_eq() {
      assert_eq!(7+2, 9); // can use any two expressions that are equal
  }
}
}

Asserting 3

// Make the tests compile and pass successfully.

pub fn is_even(num: i32) -> bool {
    num % 2 == 0
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn is_true_when_even() {
        assert!();
    }

    #[test]
    fn is_false_when_odd() {
        assert!();
    }
}

#![allow(unused)]
fn main() {
pub fn is_even(num: i32) -> bool {
  num % 2 == 0
}

#[cfg(test)]
mod tests {
  use super::*;

  #[test]
  fn is_true_when_even() {
      assert!(is_even(10));
  }

  #[test]
  fn is_false_when_odd() {
      assert!(!is_even(9));
  }
}
}

Returning result

// Complete the test function's signature.

fn calculate_sum(nums: &[i32]) -> Result<i32, String> {
    if nums.len() == 0 {
        return Err("Number list is empty".to_string());
    }
    let mut sum = 0;
    for num in nums {
        sum += num;
    }
    Ok(sum)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn calculates_sum_correctly() -> {
        let nums = [1, 2, 3, 4, 5];
        let sum = calculate_sum(&nums)?;
        assert_eq!(sum, 5 * (5 + 1) / 2);
        Ok(())
    }
}

#![allow(unused)]
fn main() {
fn calculate_sum(nums: &[i32]) -> Result<i32, String> {
  if nums.len() == 0 {
      return Err("Number list is empty".to_string());
  }
  let mut sum = 0;
  for num in nums {
      sum += num;
  }
  Ok(sum)
}

#[cfg(test)]
mod tests {
  use super::*;

  #[test]
  fn calculates_sum_correctly() -> Result<(), String> {
      let nums = [1, 2, 3, 4, 5];
      let sum = calculate_sum(&nums)?;
      assert_eq!(sum, 5 * (5 + 1) / 2);
      Ok(())
  }
}
}

Testing panics

// Add a macro to make the test pass.

fn average(nums: &[i32]) -> i32 {
    if nums.len() == 0 {
        panic!("Empty number list");
    }
    let mut sum = 0;
    for num in nums {
        sum += num;
    }
    sum / nums.len() as i32
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn it_panics() {
        let nums = [];
        let _avg = average(&nums);
    }
}

#![allow(unused)]
fn main() {
fn average(nums: &[i32]) -> i32 {
  if nums.len() == 0 {
      panic!("Empty number list");
  }
  let mut sum = 0;
  for num in nums {
      sum += num;
  }
  sum / nums.len() as i32
}

#[cfg(test)]
mod tests {
  use super::*;

  #[test]
  #[should_panic]
  fn it_panics() {
      let nums = [];
      let _avg = average(&nums);
  }
}
}